Recent advances in advanced process control (APC) in the area of semiconductor processing equipment (SPE), or tools, used by semiconductor manufacturing facilities (fabs) in the production of high performance integrated circuits, include the addition of monitoring hardware and software at the tool level (TL) that is used for the purpose of fault detection and classification (FDC). FDC provides the capability to establish a baseline of tool operation and by comparing the current operation with the baseline, detect faults as well as classify or determine the root cause of the problem. The techniques used for FDC include the use of statistical process control (SPC) charts, principle component analysis (PCA) and partial least squares (PLS). Each of these techniques provides a numerical comparison of the current operation to the baseline. Limits can then be placed around the normal value or values of this comparison and alarms can be generated whenever the comparison exceeds one or more of the numerical limits. When an alarm is generated, the process can be stopped or other action taken.
Operation of an FDC system at the tool level has the advantages of decreasing production scrap due to tool level faults, decreasing tool downtime by improving diagnostic capability and decreasing the amount of unscheduled maintenance by monitoring parts wear and scheduling preventative maintenance.
The use of feedforward controllers in semiconductor processing has long been established practice by fabs in the manufacture of semiconductor integrated circuits. Recent advances in APC used by fabs in the production of high performance integrated circuits include the addition of hardware and software at the tool level that is used for the purpose of run-to-run (R2R) control.
However, the simultaneous operation of FDC and an R2R controller can be difficult or mutually exclusive. This is because an FDC system may interrupt the R2R controller with detected faults or parameter changes to prevent faults. A conventional R2R controller is unable to integrate the information received from an FDC system and continue to run real time. This is especially true for W2W processing, which provides significantly more data to process than L2L processing.
In fact, it was previously thought that integrating FDC and R2R control was not possible, as both processes are so computationally intensive. Thus, to applicants' knowledge, integration of an FDC system and an R2R controller has never been done before. The present inventors recognized that this integration was possible, and took the necessary steps and solved the required problems to achieve the present invention.